Water Fountains
Works on a vacuum principle which maintains the level in the circular trough at the base. When water is consumed below the outlet the vacuum is broken water released until the outlet is covered by the rising water level which again stops the flow into the trough. Very efficient tried and tested drinkers, shown above from right to left as 1/2 (2.3 Litres), 1 (4.6 Litres), 2 (9.1 Litres) and 3 gallon (13.6 Litres.)
